#!pip install langchain openai weaviate-client

OPENAI_API_KEY="<YOUR_OPENAI_API_KEY>"

import dotenvdotenv.load_dotenv()

import requestsfrom langchain.document_loaders import TextLoader
url = "<https://raw.githubusercontent.com/langchain-ai/langchain/master/docs/docs/modules/state_of_the_union.txt>"res = requests.get(url)with open("state_of_the_union.txt", "w") as f:f.write(res.text)
loader = TextLoader('./state_of_the_union.txt')documents = loader.load()

from langchain.text_splitter import CharacterTextSplittertext_splitter = CharacterTextSplitter(chunk_size=500, chunk_overlap=50)chunks = text_splitter.split_documents(documents)

from langchain.embeddings import OpenAIEmbeddingsfrom langchain.vectorstores import Weaviateimport weaviatefrom weaviate.embedded import EmbeddedOptions
client = weaviate.Client(embedded_options = EmbeddedOptions())
vectorstore = Weaviate.from_documents(client = client,documents = chunks,embedding = OpenAIEmbeddings(),by_text = False
)

retriever = vectorstore.as_retriever()

from langchain.prompts import ChatPromptTemplate
template = """You are an assistant for question-answering tasks.Use the following pieces of retrieved context to answer the question.If you don't know the answer, just say that you don't know.Use three sentences maximum and keep the answer concise.Question: {question}Context: {context}Answer:"""prompt = ChatPromptTemplate.from_template(template)
print(prompt)

from langchain.chat_models import ChatOpenAIfrom langchain.schema.runnable import RunnablePassthroughfrom langchain.schema.output_parser import StrOutputParser
llm = ChatOpenAI(model_name="gpt-3.5-turbo", temperature=0)
rag_chain = ({"context": retriever,"question": RunnablePassthrough()}| prompt| llm| StrOutputParser())
query = "What did the president say about Justice Breyer"rag_chain.invoke(query)

"The president thanked Justice Breyer for his service and acknowledged his dedication to serving the country.The president also mentioned that he nominated Judge Ketanji Brown Jackson as a successor to continue Justice Breyer's legacy of excellence."